http://goireland.about.com/od/nightlife/a/sessions.htm
Enjoy 
Uilliam
Also note additional links at the bottom of that page for sessions in Belfast, Antrim and Clare.
I especially like when it says “very profesional”
I think what they want to say - shitty amplified gigs for wasted tourists.
Hey! On behalf of wasted tourists everywhere, I protest! 